Read a file line-by-line and update a line of it

readFile.js

const fs = require('fs');
const readline = require('readline');

const readFile = () => {
	// create readline interface and output to a new file; can't figure out how to write to same file
	const readInterface = readline.createInterface({
		input: fs.createReadStream(findup('sonar-project.properties')),
		output: fs.createWriteStream('sonar-project.properties.temp'),
		console: false
	});

	// read line by line and modify a line and rewrite it back
	readInterface.on('line', function(line) {
		if (line.includes('projectVersion')) {
			this.output.write('sonar.projectVersion=2020.1.0\n');
		} else {
			this.output.write(`${line}\n`);
		}
	});
};